From DE 196 02 549 A1 is known, for example, a belt tensioner for a safety belt having a belt retractor, a tensioner pinion that can be or is non-rotatably connected to the belt retractor, a tube having a pyrotechnical gas generator arranged therein, and a plurality of mass bodies that can be driven by the pressure generated by the gas generator. The mass bodies can be engaged in the tensioner pinion in a force transmitting manner and drive the belt retractor in winding direction when the belt tensioner is activated. A first section of the tube runs alongside the tensioner pinion in perpendicular direction with respect to the longitudinal axis of the belt spool, and a second section, which is opposite to the first section, is directed tangentially toward the tensioner pinion. The first section and the second section are arranged in a plane and are connected to each other by way of a third section, which is likewise located in the plane. The basic problem presented by this kind of displacement of the tube is that the mass bodies that emerge from the tensioner pinion have to be led away, so that the driving motion of the mass bodies is not disrupted by an accumulation of the mass bodies.
From DE 195 12 660 A1 is known a belt tensioner with an identical tube guide, in which a collection container is provided to accommodate the mass bodies after they emerge from the tensioner pinion. It is disadvantageous of this approach, however, that the number of mass bodies is limited due to the tube guide and the size of the collection container when mass bodies of a particular size are used.
Since the tightening length of such a belt tensioner that is to be attained is directly dependent from the number of the mass bodies, the tightening length to be attained with such a belt tensioner is thus also automatically limited.